Matrix metalloproteinases (MMPs) and their specific inhibitors (TIMPs) are thought to play an essential role in liver injury associated with tissue remodeling. However, their distinct expression profile in different liver repair models still remains to be established. Hepatic expression of collagenase (MMP-13), gelatinases A and B (MMP-2, -9), stromelysin-1 and -2 (MMP-3, -10), membrane-type MMP-1 (MMP-14), and TIMP-1 and -2 was studied following single and repeated CCl 4 -mediated injury and after partial hepatectomy. Expression was analyzed by reverse transcription-PCR (RT-PCR), northern blot analysis, zymography, and immunohistochemistry. Following a single toxic liver injury, MMPs and TIMPs were induced in a distinct time frame in that expression of most MMPs was induced during the early phase of liver injury, was maximal during the inflammatory reaction, and was diminished in the recovery phase. In contrast, TIMP and MMP-2 steady state mRNA levels remained constant in the early phase, were strongly induced during tissue inflammation, and remained increased until the recovery phase. Interestingly, hepatic TNF-α expression paralleled the MMP induction profile, while the increase of TGF-β1 expression mapped to the increase of TIMPs. Chronic liver injury was accompanied by an increase in the steady state mRNA levels of MMP-2 and TIMPs, while other MMPs remained more or less unchanged or were diminished. Partial hepatectomy was followed by a dramatic increase of MMP-14 and to a lesser extent also of TIMP-1 expression; other MMPs and TIMPs were not significantly induced. Liver injury is accompanied by profound changes in hepatic MMP/TIMP expression, the latter being critically dependent on the type of injury. Single toxic injury resulting in complete restoration was characterized by a sequential induction of MMPs and TIMPs suggesting initial matrix breakdown and matrix restoration thereafter. Chronic liver injury leading to fibrosis displays overall diminished matrix degradation mainly through TIMP induction, while liver regeneration induced by partial hepatectomy caused an induction of MMP-14 and TIMP-1 only, which might be unrelated to matrix turnover but connected to pericellular fibrinolysis or fibrolysis required for hepatocellular replication.

Hepatitis C virus (HCV) frequently causes chronic liver disease. The cause of viral persistence might be an inappropriate type I interferon (IFN) induction. To analyze the host's IFN response in chronic hepatitis C, we measured the transcription level of type I IFN genes as well as type I IFN-regulated genes in liver tissue and corresponding blood samples from patients with chronic hepatitis C, nonviral liver diseases, and a suspected but later excluded liver disease. Competitive and real-time RT-PCR assays were used to quantify the messenger RNA (mRNA) levels of all known IFN-a, IFN-b, and IFN-k genes and those of some IFN-regulated genes. We failed to detect any hepatic type I IFN mRNA induction, although liver tissue of chronic hepatitis C patients contained high numbers of some type I IFN-inducible effector mRNA molecules. Analysis of peripheral blood samples, however, showed a clear type I IFN induction. Parallel experiments employing HCV replicon cell lines revealed that replication of HCV RNA is not sufficient to induce any type I IFN nor to induce directly type I IFN-regulated genes such as MxA. In conclusion, our data provide evidence for the absence of an induction of type I IFN genes by HCV in the human liver and argue for a further development of type I IFN-based therapies.

The insulin-like growth factors I and II (IGF-I, -II) are circulating peptides known to participate in the regulation of metabolism, growth, and cellular differentiation. In the present study, ''early cultured'' (days 2-3 of culture) and ''culture-activated'' (days 6-7 of culture) rat hepatic stellate cells ( The insulin-like growth factors I and II (IGF-I and IGF-II) are structurally related polypeptides involved in various metabolic, proliferative, and differentiation processes mediated by endocrine, autocrine, and paracrine mechanisms.

The adult liver is the main source of circulatingThe insulinlike growth factors (IGF-I and IGF-II) are insulinlike growth factors (IGFs ) and their serum circulating peptides with structural homology to proinbinding proteins (IGFBPs) including the acid-labile sulin. 1,2 They are known to participate in the regulation subunit (ALS), a component of the ternary binding of growth, metabolism, and cellular differentiation. 3 protein complex. Within the liver, the biosynthesis of The adult liver has been recognized as the major site individual proteins has been attributed to different of IGF biosynthesis. 4,5 cell populations, e.g., that of ALS to hepatocytes andIn serum, IGFs bind with high affinity to specific that of IGFBP-3 to nonparenchymal cells. Ligand and binding proteins. So far, six distinct binding proteins immunoblotting as well as Northern blotting analyses (named IGFBP-1 to -6) have been identified. 6 In the 3, and of the acid-labile subunit (ALS). 7,8 Formation ofsynthesis of IGFBP-1, -2, and -4 was observed; insulin and IGF-I decreased that of IGFBP-1, and -2 while in-this ternary complex is believed to prolong half-life of creasing that of IGFBP-4. KCs synthesized IGFBP-2, IGFs in systemic circulation 9 and to prevent acute insuand -3, insulin and IGF-I showing no effect. In cocul-linlike actions of these peptides, i.e., hypoglycemia. In tures, however, synthesis of IGFBP-3 was stimulated addition, IGFs form binary complexes with other by insulin and IGF-I. By immunocytochemistry IGFBPs (e.g., IGFBP-1, -2, and -4) of 31 to 40 kd that IGFBP-3 biosynthesis was localized to KCs exclu-are capable of crossing capillary walls and facilitating sively. When pore membranes were used for separa-IGF transport to target tissues. 10 tion of hepatocytes and KCs in coculture, this in-The biosynthesis of serum IGFBPs has been localized sulin-stimulatory action on IGFBP-3 synthesis was to the liver, too. 11 Recently, several studies in rats have size this glycosylated 82-to 88-kd protein. 16,17 Regulation of biosynthesis of individual IGFBPs and of ALS is not uniform and apparently linked to condi- Before the addition of hormones, cultures and cocultures of rat liver cells specific activity of approximately 60 to 80 mCi/mg. Porcine insulin, dexamethasone, and glucose oxidase were obtained were washed with the M-199 medium supplemented with 0.2% (wt/vol) BSA and then incubated in the culture medium from Sigma Chemical Co. (Deisenhofen, Germany). Human GH was kindly donated by Nordisk (Mainz, Germany). En-at 37ЊC for 1 hour. The medium was then replaced by fresh medium supplemented with 0.2% (wt/vol) BSA, and the cells zymes, fetal calf serum (FCS), and M-199 medium were purchased from Boehringer Mannheim (Mannheim, Germany). were incubated in the presence or absence of insulin, IGF-I, and GH in concentrations ranging from 0.1 to 100 nmol/L Bovine serum albumin (BSA), glucagon, and antibiotics were from Serva Feinbiochemica Gmbtt & Co. KG (Heidelberg, each for 36 hours.Immunocytochemistry. For immunocytochemical analys...

We are the first to report a gene expression signature for the in vitro chemoradiosensitivity of colorectal cancer cells. We anticipate that this analysis will unveil molecular biomarkers predictive of the response of rectal cancers to chemoradiotherapy and enable the identification of genes that could serve as targets to sensitize a priori resistant primary tumors.